html,body {height: 100%;}

body {
  display: -ms-flexbox;
  display: -webkit-box;
  display: flex;
  -ms-flex-align: center;
  -ms-flex-pack: center;
  -webkit-box-align: center;
  align-items: center;
  -webkit-box-pack: center;
  justify-content: center;
  padding-top: 40px;
  padding-bottom: 40px;
  background-color: #333;
}

.form-signin {
  width: 100%;
  max-width: 430px;
  padding: 15px;
  margin: 0 auto;
}

.form-signin .form-control{font-size: 16px;}

.form-signin .input-group-header .input-group-prepend .input-group-text{border-bottom-left-radius: 0; border-bottom: 0px;}
.form-signin .input-group-header .form-control{border-bottom-right-radius: 0; border-bottom: 0px;}
.form-signin .input-group-footer .input-group-prepend .input-group-text{border-top-left-radius: 0;}
.form-signin .input-group-footer .form-control{border-top-right-radius: 0;}
.form-signin button[type="submit"]{margin-top: 20px;}